U.S. patent application Ser. No. 09/453,729, filed Dec. 2, 1999 entitled “Cellular Coal Products and Processes” describes coal-based cellular or porous products having a density of preferably between about 0.1 g/cm3 and about 0.8 g/cm3 that are produced by the controlled heating of coal particulate preferably up to 1 mm in diameter in a “mold” and under a non-oxidizing atmosphere. The porous products produced by these processes, preferably as a net shape or near net shape, can be machined, adhered and otherwise fabricated to produce a wide variety of low cost, low density products, or used in its preformed shape as a filter, heat or electrical insulator etc. Such cellular products have been shown to exhibit compressive strengths of up to about 4000 psi. Impregnation with appropriate materials or the incorporation of various strength improving additives can further increase the compressive, tensile and other properties of these cellular materials. Further treatment by graphitization yields cellular products that can be used as electrical or heat conductors.
The coal-based products described in the foregoing U.S. patent application have many potential uses that are supported by their low densities, high strengths, thermal and electrical conductivities and fluid permeabilities, however, many such applications or uses require combinations of such properties in order to provide the desired product. For example, while low density and relatively high strength may be required for a specified use, attachment of the coal-based foam product demonstrating such low density and relatively high strength may require the inclusion of a very high strength region in a portion of the product part to permit the passage of a fastener that will induce areas of high mechanical stress in the area of fastener passage. Similarly, while fluid permeation of the coal-based cellular product may be desired in one direction, it may be necessary to limit or inhibit such fluid permeation in orthogonal directions to achieve directed fluid flow as through a “pipe”. It can also be envisioned that a low-density coal-based product part may require the inclusion of high strength regions to provide structural properties in regions thereof that are subjected to elevated directional mechanical stresses that the bulk of the low density material cannot adequately support.
Thus, it would be highly desirable to be able to custom design various regions of the coal-based cellular product to support various different strength, thermal and electrical conductivity and fluid permeation properties in the various regions of the coal-based cellular product. Stated differently, it would be highly desirable to possess the ability to provide coal-base cellular products and parts produced from a single cell forming process that exhibit integral: 1) stiffeners or load paths; 2) directed heat or electrical transfer paths; and 3) directed mass transfer paths.